Collapsible loop aerial



March 12', 1929. MATHlESEN 1,705,262

COLLAPS IBLE LOOP AERIAL Filed March 1925 2 Sheets-Sheet l Mar/11,5Mal?) aka 6]? March 12, 1929. M. MATHIE SEN 1,7 5 262 GOLLAPSIBLE LOOPAERIAL Filed March 1925 2 Sheets-Sheet 2 T m 7 a g aw 3 age 4 w 5 mm 2CO a a 4 2 M M Wu a a a A 0 M QNW x5 7 Patented Mar. 12, 1929.

UNITED STATES PATENT OFFICE.

MARIUS MATIIIIJSEN, OF CHICAGO, ILLINOIS, ASSIGNOR, BY .ASSIGNI IENTS,TO WILLIAM J. SANDBERG.

COLLAPSIBLE LOOP AERIAL.

Application filed March 6, 1925.

hl'y invention relates to loop aerials and has special. reference toimprovements in collapsible loop aerials.

The object of my invention to provide a loop aerial which can bemanufactured at relatively low cost, which can be readily collapsed intoa compact form for shipment, which shall he likewise readily arranged inextended form for use, which shall have simple means for properlytensioning the plurality of turns of wire thereon.

A further feature of my invention relates to a base upon which theaerial is mounted to be swung around on a vertical axis and means forremovably retaining the base on the aerial for the purpose of making thedevice readily portable, as a unit, when in extended condition.

Another feature relates to an improved manner of making the lower end ofthe mast whereby the projection of the lower cross bar through the mastis simplified.

My invention will be more readily understood by reference to theaccompanying drawings forming part of this specification and in whichFigure l, is a perspective view of a collapsible loop aerial made inaccordance with my invention; v

Figure 2, is a fragmentary elevation of the center of the frame as itwould. appear with one clamping plate removed;

Figure 3, is an elevational view of the frame shown collapsed to acompact bundle;

Figure 4;, is a fragmentary, vertical, central section on the line 4.-4of Figure 1.;

Figure 5, a fragmentary, vertical section on the line 5--5 of Figure 1;

Figure 6, is a fragmentary, vertical, central section on the line 6-6 ofFigure 1;

Figure 7, is a fragmentary, vertical section on the line 7-7 of Figure1;

Figure 8, is a vertical, central section on the line S8 of Figure 7 andFigure 9, is a horizontal section on the line 9-9 of Figure 8.

In said. drawing, 10 represents generally a collapsible frame comprisingan upper vertical arm 11 and a lower vertical arm '12 and two horizontalarms 13 and 14. At the ends of the arms are secured cross members 15 onwhich the aerial wire 16 is wound in the form of a plurality of turns17. The four arms radiate from a common center where means, to be morefully described Serial No. 13,599.

hereinafter, are provided for clamping then'r firmly together and forforcibly radially projecting sone of the arms during the clampingoperation to properly tension the turns 17 of the wire 16.

At the lower end of the lower vertical arm 1." I provide means fornormally holding the frame in vcrtiral position and permitting to beswung around on a vertical axis, so that the one using it can readilyset it to obtain the best results. This swivelling mounting comprises avertical fixed spindle 18 secured upright in a suitable base 19 or othersupport. The lower end of the arm 12 is provided with an axial opening19 to receive the spindle 18. To make "the lower end of the arm 12 moredurable I g novide a tubular casing 20 for ill'iiS end and throughwhich, as well as through the arm, the lowermost cross memher l5projects.

The means at the center of the frame for clamping and. spreading thearms comprises two opposed clamping plates 21 and 22. Each of theseplates is formed with a radial arm 23 for each of the arms of the frame10 and the side edges of each of these arms are bent inwardly to formedge flanges 24 so that when the arms are opposed a socketis presented.for the inner end of each of the arms of the frame. I provide a centralclamping bolt 25 which I preferably rigidly secure at one end in theplate 22 and adapted to project lhrougl'i. a central. opening in theopposite plate 21. Preferably I provide a winged nut 25 on the screw forclamping the two plates tightly upon the assembled inner ends ot thearms. lVheu the plates are tightly clamped upon the arms they are heldrigidly projecting to form the frame 10.

In order to render it an easy operation to place the arms with theirinner ends together and the plates upon them ready to he clamped, Iprovide means whereby the arms can be. 'aced in such position withoutthe necessity of completely tensioning the loop wire 16. For thispurpose I provide a removable block 26 for placement between the inneradjacent ends of the arms of the finale. Two of the contacting sides 27of the block 26 are square, as shown in Figure (l, and the, other twoopposing sides 2? are inclined to make the block in the form of a tactwith the sides 28 are correspondingly inclined. This constructionpermits the assembly of the block 26 with the arms and the plates, asindicated in dotted lines in Figure 4-, wherein the block 26 is shown asjust started in between the adjacent ends of the arms of the frame. Thenthe plates 22 and 21 are placed in position, the bolt 25 being )rojectodthrough a central opening 30 in the block 26. The bolt 25 is long enoughso that the nut 25 can be entered upon the bolt at this time, and uponscrewing the nut home the plates '21 and 22 are clamped tightly togetherupon the arms of the frame, during which. process the wedging bloc G isforced inwardly between the arms torcibly relatively projecting at leasttwo of the arms radially outward and thus tensioning the loop wire.

As the loop aerial is easily portable, I provide means for yieldinglyretaining the base 19 and the frame together so that if the devicepicked up by the frame work the base will. not drop off. For thispurpose I provide a spring pressed ball 31 in the upper end of thespindle 18. This ball is mounted in a transverse pocket 32 in the upperend of the spindle and constantly to red outwardly by a spring 33 in thepoohet 32 beneath the ball 31. The mouth of the pocket 32 is slightlycompressed after the ball is inserted to prevent the escape and loss ofthe ball. As best shown in Figure 7 the ball is projected beyond thecylindrical surface of the spindle 18 and over the "top of a tubularbushing 34 which I insert into the lower end of the arm 12. lVhen thebase 19 is forcibly withdrawn from the frame the ball is pushed backinto the pocket 32 and likewise when the base and frame are assembled.This construction permits the frame to swing around on the spindle 18but prevents the base being inadvertently dropped olf.

All but the lower cross piece can be readily secured on the outer endsof the several arms, but this lower one is projected through the lowerend of the lower part 12 of the mast. I have devised a very simple wayin which to effect the insertion of this lower cross piece in throughthe mast. First I cut a vertical central slot 35 in the lower end of themast which extends from the lower end up to the upper edge of the lowercross piece 15 and of a width to receive the piece 15, as best shown inFigure 8. The tubular casing reinforces this lower end and is providedwith suitable openings to permit the projection of the cross piece 15through same. I first assemble the cross piece with the tube and thenplace both on the mast together, sliding the cross piece up through theslot to its upper end. To permanently retain the cross piece in positionI drive a block 36 into the slot to fill the same below the cross piece15. Then I make the central vertical opening 19 in the lower end of themast to receive the bearing tube This construction is very cheaply madeis very durable. Instead of the inner ends of the arms ll, 12, i3 and1-1 being entirely free of each otl er, sometir ior z prefer to hingethe two horizontal arms 13 and l i to the upper end of the lower part 12of the mast. This construction is best shown in Figure 2, the hinges 37being preferably let into t'l'ie sides of the arms to avoid the flanges2% on the plates 21 and 22.

As many modifications of my invention will readily suggest themselves toone skilled in the art, I do not limit or conline my invention to thespecific details of construction herein shown and described.

I claim:

1. In a collapsible loop aerial, a plurality of pairs of arms arrangedto radiate from a center, clamping plates for binding the inner ends ofthe arms together, a wedge block for intorpositioning between the innerends of the arms, clamping plates between which the wedge block isarranged and a screw bolt passing through the plates and the wedge blockfor securing the parts in loop extended relation.

2, In a loop aerial of the kind described, a mast adapted to beswive'lly mounted at its lower end, a cross bar for Wires projectedthrough the mast adjacent to its lower end, a reinforcing tube on thelower end of the mast, the mast slotted longitudinally for permittingthe assembly of the parts, and means closing the slot below theassembled position of the cross arm.

3. In a loop aerial of the kind described, a mast adapted to be swivellymounted at its lower end, a cross bar for wires projected through themast adjacent to its lower end, a reinforcing tube on the lower end ofthe mast, the mast slotted longitudinally for I," ermitting the assemblyof the parts, means closing the slot below the assembled position of thecross arm, and a tube inserted in the lower end of the mast to form abearing.

4. In a collapsible frame for a loop aerial, a plurality of arms adaptedto be arranged in loop extended condition, radiating from a center,clamping plates for holding the inner ends of the arms together, theplates formed with radiatingarms bent at their edges to engage aroundthe inner ends of the frame arms, as and for the purpose specified and awedge block between the plates and adapted to be forced into alignmentwith the arms by the plates.

5, in a collapsible loop aerial, a plurality of arms adapted to bearranged, in extended relation, radiating from a. center, a pair ofopposed clampin plates, the plates formed with radial arms bent in attheir edges and adapted to provide sockets for the inner ends of theframe arms and means for clamping the plates tightly upon the inner endsof the frame arms, as and for the purpose specified and a wedge adaptedto be arranged between the inner ends of one pair of arms and to be heldin position by the plates.

6. In an aerial loop frame of the kind described, a mast, a cross memberabove the lower end of the mast, the lower end of the mast provided witha central slot projecting up from its lower end, a tubular reinforcingmember for the lower end of the mast, provided with oppositely disposedopenings through which the cross member can be pro jeeted, the slot inthe mast permitting the assembly of the cross member and the tubularmember with the mast after the cross member has been projected throughthe tubular member, and means for permanently retaining the parts inassembled relation.

In testimony whereof, I have hereunto set my hand, this 27th day ofFebruary, 1925.

MARIUS MATHIESEN.

